全文获取类型
收费全文 | 1580篇 |
免费 | 70篇 |
专业分类
各国政治 | 96篇 |
工人农民 | 63篇 |
世界政治 | 124篇 |
外交国际关系 | 105篇 |
法律 | 866篇 |
中国共产党 | 2篇 |
中国政治 | 18篇 |
政治理论 | 331篇 |
综合类 | 45篇 |
出版年
2023年 | 12篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 42篇 |
2019年 | 47篇 |
2018年 | 63篇 |
2017年 | 72篇 |
2016年 | 67篇 |
2015年 | 44篇 |
2014年 | 57篇 |
2013年 | 262篇 |
2012年 | 60篇 |
2011年 | 67篇 |
2010年 | 76篇 |
2009年 | 62篇 |
2008年 | 74篇 |
2007年 | 58篇 |
2006年 | 55篇 |
2005年 | 65篇 |
2004年 | 54篇 |
2003年 | 39篇 |
2002年 | 51篇 |
2001年 | 37篇 |
2000年 | 33篇 |
1999年 | 19篇 |
1998年 | 27篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 2篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1972年 | 2篇 |
1967年 | 3篇 |
1963年 | 1篇 |
排序方式: 共有1650条查询结果,搜索用时 15 毫秒
91.
92.
93.
The purpose of this study was to evaluate the ability of two amphetamine class screening reagents to exclude ephedrine (EPH), pseudoephedrine (PSEPH), and phenylpropanolamine (PPA) from falsely producing positive immunoassay screening results. The study also sought to characterize the prevalence and concentration distributions of EPH, PSEPH, and PPA in samples that produced positive amphetamine screening results. Approximately 27,400 randomly collected human urine samples from Navy and Marine Corps members were simultaneously screened for amphetamines using the DRI and Abuscreen online immunoassays at a cutoff concentration of 500 ng/mL. All samples that screened positive were confirmed for amphetamine (AMP), methamphetamine (MTH), 3,4-Methylenedioxyamphetamine (MDA), 3,4-Methylenedioxymethamphetamine (MDMA), EPH, PSEPH, and PPA by gas chromatography/mass spectrometry (GC/MS). The DRI AMP immunoassay identified 1,104 presumptive amphetamine positive samples, of which only 1.99% confirmed positive for the presence of AMP, MTH, MDA, or MDMA. In contrast, the online AMP reagent identified 317 presumptive amphetamine positives with a confirmation rate for AMP, MTH, MDA, or MDMA of 7.94%. The presence of EPH, PSEPH, or PPA was confirmed in 833 of the 1,104 samples that failed to confirm positive for AMP, MTH, MDA, or MDMA; all of the 833 samples contained PSEPH. When compared to the entire screened sample set, PSEPH was present in approximately 3%, EPH in 0.9%, and PPA in 0.8% of the samples. The results indicate that cross reactivities for EPH, PSEPH, and PPA are greater than reported by the manufacturer of these reagents. The distribution of concentrations indicates that very large concentrations of EPH, PSEPH, and PPA are common. 相似文献
94.
Accident investigation is frequently cited as the cornerstone of an effective occupational health and safety program. We suggest that the literature on accident investigation is based on a model of witnesses as neutral and accurate recording devices. The literature on eyewitness testimony and criminal investigation offers strikingly different conclusions. We review these findings and point to their implication for research on accident investigation in occupational health and safety contexts. 相似文献
95.
De Letter EA Bouche MP Van Bocxlaer JF Lambert WE Piette MH 《Forensic science international》2004,141(2-3):85-90
The amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy" is a currently used or abused designer drug and fatalities are frequently encountered in forensic practice. However, the question remains open whether an MDMA blood level can be toxic or even potentially lethal. In order to provide insight in the interpretation of a detected MDMA concentration, the distribution of MDMA and its metabolite 3,4-methylenedioxyamphetamine (MDA) in various body fluids and tissues was studied and discussed in two different fatalities. Apart from peripheral blood samples (such as femoral and subclavian blood), various blood samples obtained centrally in the human body and several body fluids (such as vitreous humour) were examined. In addition, various tissues such as cardiac muscle, lungs, liver, kidneys, and brain lobes were analysed. In contrast to the peripheral blood levels, high MDMA and MDA levels were found in cardiac blood and the majority of the organs, except for the abdominal adipose tissue. The high concentrations observed in all lung lobes, the liver and stomach contents indicate that post-mortem redistribution of MDMA and MDA into cardiac blood can occur and, as a result, blood sampled centrally in the body should be avoided. Therefore, our data confirm that peripheral blood sampling remains "the golden standard". In addition, a distinct difference in peripheral blood MDMA concentrations in our two overdose cases was established (namely 0.271 and 13.508 microg/ml, respectively). Furthermore, our results suggest that, if a peripheral blood sample is not available and when putrefaction is not too pronounced, vitreous humour and iliopsoas muscle can be valuable specimens for toxicological analysis. Finally, referring to the various mechanisms of death following amphetamine intake, which can result in different survival times (e.g. cardiopulmonary complications versus hyperthermia), the anatomo-pathological findings and the toxicological results should be considered as a whole in arriving at a conclusion. 相似文献
96.
McCusker PJ Moran MJ Serfass L Peterson KH 《International journal of offender therapy and comparative criminology》2003,47(5):585-596
Relationships among Structured Interview of Reported Symptoms (SIRS) scores and Minnesota Multiphasic Personality Inventory--2 (MMPI-2) F(p) and F scores were examined for 63 suspected malingerers evaluated at either of two psychiatric facilities. Despite differences between facilities in terms of seriousness of subjects' offenses, mean scores on the malingering tests were similar. Cutting scores for F(p) and F resulting in substantial correspondence between these scales and the SIRS were derived. Use of the cut score for F(p) proposed by Arbisi and Ben-Porath (1995) resulted in less agreement with the SIRS than did a lower cut score. No substantial difference between F(p) and F in each scale's overall agreement with the SIRS was observed. A principal components analysis of the SIRS primary scales produced two factors, interpreted as Overreporting of Symptoms and Implausible Symptoms. F(p) was observed to correlate significantly with Implausible Symptoms but not with Overreporting of Symptoms; F was significantly correlated with both factors. 相似文献
97.
Some previous research indicates that confidence affects the accuracy of probabilistic clinical ratings of risk for violence among civil psychiatric inpatients. The current study investigated the impact of confidence on actuarial and structured professional risk assessments, in a forensic psychiatric population, using community violence as the outcome criteria. Raters completed the HCR-20 violence risk assessment scheme for a sample of 100 forensic psychiatric patients. Results showed that accuracy of both actuarial judgments (HCR-20 total scores) and structured professional judgments (of low, moderate, and high risk) were substantially more accurate when raters were more confident about their judgments. Findings suggest that confidence of ratings should be studied as a potentially important mediator of structured professional and actuarial risk judgments. 相似文献
98.
A method was developed to screen for pepper spray residue using instruments and methods other than those techniques commonly employed to analyze chemical residue (i.e.. gas chromatography mass spectrometry-GCMS or liquid chromatography mass spectrometry-LCMS). The method employed gas chromatography (GC), thin layer chromatography (TLC), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to screen for dried pepper spray stains. Pepper sprays from nine different manufacturers were investigated. Capsaicin and dihydrocapsaicin were identified and unique IR reflectance spectra are presented. An additional five compounds were presumptively found. Results showed that a particular stain could be characterized as a pepper-based stain. 相似文献
99.
The presence of cocaine in illicit drug samples is still being determined in some laboratories using spot tests and microcrystal tests. Seventeen chemical species were tested using three different spot tests (Wagner, Marquis, and cobalt thiocyanate followed by stannous chloride reactions) and two microcrystal tests (gold chloride and platinic chloride) to determine whether the results could be differentiated from the results of these tests on cocaine. The data obtained indicated that nine of the 17 compounds gave results similar to those from cocaine using the three spot tests, but that the results from microcrystal testing allowed for differentiation of all nine compounds from cocaine. 相似文献
100.